Coal plant offsets with carbon capture means covering 89 percent of the US in forests

Researchers found that using bio-sequestration to capture carbon produced by US coal-fired plants even after carbon capture and storage would require using 62 percent of the nation's arable land for that process, or 89 percent of all US land with average forest cover. Credit: Rylie Kostreva, Michigan Tech

Researchers found that using bio-sequestration to capture carbon produced by US coal-fired plants even after carbon capture and storage would require using 62 percent of the nation's arable land for that process, or 89 percent of all US land with average forest cover. In comparison, offsetting the amount of carbon produced by manufacturing solar panels is 13 times less land, making it a far more viable option.

While demand for energy isn't dropping, alarms raised by burning fossil fuels in order to get that energy are getting louder. Often suggested solutions to cancel out the effects of the carbon dumped into our atmosphere through carbon capture and storage or bio-sequestration. This zero-emission energy uses technical means as well as plants to take in carbon emissions and store it. Another route is to use solar photovoltaics to convert sunlight directly into electricity and only sequester the carbon emissions from the production of solar cells.

The Giving Tree Won't Give Enough for Carbon Neutral Coal

Zero-emission energy has been offered as a way to offset the carbon dioxide production while still maintaining coal's electricity generation. That's done through carbon capture and storage in saline aquifers or using enhanced oil recovery as well as bio-sequestration by planting trees and other plants to suck up and store carbon.

In a new study published in Scientific Reports, a Nature publication, Michigan Technological University researchers looked at how much land would be required to offset greenhouse gases created by traditional coal-fired plants or coal-fired plants with carbon sequestration and then neutralizing the remaining carbon pollution with bio-sequestration. Then it compared these routes to how much bio-sequestration would be required to offset greenhouse gases produced when making solar panels.

For the first time, researchers have shown that there is no comparison. It's not even close. Coal-fired power plants require 13 times more land to be carbon neutral than the manufacturing of solar panels. We'd have to use a minimum of 62 percent of U.S. land covered by optimal crops or cover 89 percent of the U.S. with average forests to do it.

"We know that climate change is a reality, but we don't want to live like cavemen," says Joshua Pearce, professor of material sciences and electrical engineering at Michigan Tech. "We need a method to make carbon neutral electricity. It just makes no sense whatsoever to use coal when you have solar available, especially with this data."

Coal-fired power plants require 13 times more land to be carbon neutral than the manufacturing of solar panels. Credit: Vassilissa Semouchkina, Michigan Tech

Coal-Fired Power Plant Emissions are Too Big to Solve

Researchers drew these conclusions from over 100 different data sources to compare energy, greenhouse gas emissions and land transformation needed to carbon neutralize each type of energy technology.

A one-gigawatt coal-fired plant would require a new forest larger than the state of Maryland for all of its carbon emissions to be neutralized.

They found that applying the best-case bio-sequestration for all the greenhouse gases produced by coal-fired power plants would mean using 62 percent of the nation's arable land for that process, or 89 percent of all U.S. land with average forest cover. A one-gigawatt coal-fired plant would require a new forest larger than the state of Maryland for all of its carbon to be neutralized without CCS.

In comparison, solar cells require 13 times less land to become carbon neutral and five times less than the best-case coal scenario.

"If your goal is to make electricity without introducing any carbon into the atmosphere, you should absolutely not do a coal plant," he says. Not only is it not realistic to capture all the carbon dioxide they release, but burning coal also puts sulfur dioxide and nitrous oxide and particulates in the air. They cause air population, which is already estimated to cause 52,000 premature deaths per year

Solar is a Better Zero-Emission Option—and Can Be Improved Too

Pearce says that, in these calculations, he and his team were generous to coal-fired power plants in how efficient carbon capture and storage could ideally be when scaled up. They also did not consider new ways that solar farms are being used to make them even more efficient, like using higher efficiency black silicon solar cells, putting mirrors in between rows of panels so that the light that falls between them would also be absorbed, or planting crops between rows (agrivoltaics) to get the most use out of the land dedicated to solar panels that they can.

Resources should be put towards improving the efficiency of solar panels and of solar farms, he says, not carbon capture of fossil fuel-powered plants in an attempt to become zero-emission energy, not when this data shows it isn't realistic to make big difference in protecting our changing climate.

More information:
James Gunnar Groesbeck et al, Coal with Carbon Capture and Sequestration is not as Land Use Efficient as Solar Photovoltaic Technology for Climate Neutral Electricity Production, Scientific Reports (2018). DOI: 10.1038/s41598-018-31505-3

Citation:
Coal plant offsets with carbon capture means covering 89 percent of the US in forests (2018, September 7)
retrieved 25 May 2019
from https://phys.org/news/2018-09-coal-offsets-carbon-capture-percent.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.

User comments

What the Hell is "13 times less"????Is it 1/13, 13%? No and no.I hear this kind of thing in advertising, quite often and that iswhere it belongs, because it is BS math.Absolutely meaningless and nonsensical.Unless you actually Mean to say a Negative 1300%. Doubtful.In contrast, 13 times More would be 1300% + the original 100% = 1400%.Advertising often misquotes this by saying "14 times more".This is a scientific site and no place for such BS math.

"The results show that because of lower exergy efficiencies coal plants emit 13–18 times more GHG and transform 5–13 times more land than PV. ..Carbon capture and storage and enhanced oil recovery can improve coal performance, but for all cases the results clearly show that PV is a far more effective use of land. "

*Exergy efficiency calculates the efficiency of a process taking the second law of thermodynamics into account.

Once you have grown a forest, you aren't capturing (much) more carbon. You are simply replacing the trees that die. When they die, I guess some of the carbon does wind up becoming soil, but most goes back into the atmosphere? So you reach something close to a steady state which will not take up significantly more carbon.

Total; BS. as others point out the forest when grown stops capturing significant amounts of CO2 and as the trees die, it adds CO2 back to the atmosphere. The PV numbers are simply wrong. Since solar only works in daylight and when no snow is on the panels or no dust, no rain, no thick clouds most of the time the panels generate between zero and a small fraction of rated output. PV systems in place today only work about a third of the time and most of that time is not at peak output. That means to get the current load capacity you build three times the number of plants you build using nuclear or fossil fuel and at night the power turns off. This study neglects to mention that.

Somebody Tweet the revolting POTUS. He "digs coal". The 13 times less thing also annoys me. It might have been better to say, "approximately 1/8". But...who does maths well these days? Most people are only semi-literate and getting dumber by the year.

. PV systems in place today only work about a third of the time and most of that time is not at peak output.

You can estimate the output of solar power at 1/10 to 1/8 of the nominal capacity depending on latitude. In very good locations like on a desert right on the equator it can be better.

The first reason is daylight time. 50% of the time it's night. The second reason is sun angle: the power output is sinusoidal with a theoretical average of 70% of the available (35%). The third reason is that PV cells' efficiency drops at low sun angles, the fourth reason is cloud coverage that blocks the sunlight, and the fifth reason is dirt on the panels.

But the main point is that in order to integrate the solar power into the grid, you need almost 1:1 of something else to generate the power you need when the sun is not up, so for 80-90% of the energy you use, you're drawing power from that other source. That power is typically not carbon-free but from natural gas.

So the question of replacing coal with solar is actually almost entirely about replacing coal with natural gas, and a tiny bit of solar power, assuming we can't build any more hydroelectric power or afford terribly large batteries.

And with natural gas still producing about 1/3 the CO2 emissions, you're still facing the same issue of where to put the carbon.

Oh yeah, all those tanks and submarines and aircraft which run on coal are the backbone of our defense.

says gkam

So what is your recommendation of the right kind of fuel to run all of these military equipment?Perhaps you would prefer them to run on PV or windmills? Hydro and thermal is out. Nuclear is already a source of energy for ships to run on. Or perhaps you would prefer that the US didn't bother with national security at all? Being that you live in California, the latter would be most likely.

Oh yeah, all those tanks and submarines and aircraft which run on coal are the backbone of our defense.

says gkam

So what is your recommendation of the right kind of fuel to run all of these military equipment?

Surveillance_Egg_Unit

So you think that USA military equipment currently runs on coal?I am strangely unaware that USA tanks submarines and aircraft currently runs on coal. I guess then the USA Americans haven't bothered to improve their military equipment much since the Victorian era. Does the USA army still use swords?

Keep on coding @Old_C, because you would not be a good environmentalist or climatologist.

Coal is just a nasty fossil fuel. It as a pollution footprint that is quite large. Some of the pollutants include Mercury some low-level radioactivity such as radon and other nasty stuff. And you end up with a big mess of fly ash that's also is a source of low-level radiation. These pollutants tend to concentrate all around a 100 mile radius of the of the plants with higher concentrations the closer you get. And these have recorded Health consequences.

"Researchers found that using bio-sequestration to capture carbon produced by US coal-fired plants even after carbon capture and storage would require using 62 percent of the nation's arable land for that process, or 89 percent of all US land with average forest cover."

The entire premise of this article is false. We don't need to bio-sequester carbon. Carbon dioxide is good for life. Carbon dioxide is not a bad thing. Every plant using photosynthesis needs carbon dioxide. This world is losing its collective mind.

Oh yeah, all those tanks and submarines and aircraft which run on coal are the backbone of our defense.

says gkam

So what is your recommendation of the right kind of fuel to run all of these military equipment?

Surveillance_Egg_Unit

So you think that USA military equipment currently runs on coal?I am strangely unaware that USA tanks submarines and aircraft currently runs on coal. I guess then the USA Americans haven't bothered to improve their military equipment much since the Victorian era. Does the USA army still use swords?

The entire premise of this article is false. We don't need to bio-sequester carbon. Carbon dioxide is good for life. Carbon dioxide is not a bad thing. Every plant using photosynthesis needs carbon dioxide. This world is losing its collective mind.

Homebrook

Wow that is a stupid assertion. Because life needs SOME CO2, life cannot have too much of it?We need vitamins. Vitamins are not a bad thing. So why don't you take a million vitamin tables all at once and see what happens?

If you breathed in pure CO2, it would almost instantly kill you. CO2 needed for photosynthesis doesn't change that fact.

If there is too much CO2 in the atmosphere, the global climate will get too warm. CO2 needed for photosynthesis doesn't change that fact.

It isn't the world that is losing its collective mind but rather something wrong with yours.

Once you have grown a forest, you aren't capturing (much) more carbon. You are simply replacing the trees that die

This is like saying that a human population will eventually be all adults. Trees are constantly growing, dying, and being replaced.

No, you'd need enough to suffocate you, it's not a poison!God you are a paranoid fool

CO2 is a poison.

"Its main mode of action is as an asphyxiant, although it also exerts toxic effects at cellular level. At low concentrations, gaseous carbon dioxide appears to have little toxicological effect. At higher concentrations it leads to an increased respiratory rate, tachycardia, cardiac arrhythmias and impaired consciousness. Concentrations >10% may cause convulsions, coma and death."

The amount of sun and wind isn't totally random. The yearly averages are fairly constant (well, duh,...they are both driven by the sun which has a pretty constant output)

Clouds are also not totally random. There is such a thing as meteorology, you know?

Yes: storage is a must. But it's only really necessary once your energy mix reaches that percentage where it cannot compensate for the variability (the US is still far, far, FAR from that value...other countries with lots more renewable energy in the mix have no issues at all with power stability year round - and none of them have really started in on storage, yet)

As for night: Power demand at night is comparatively low. While power output from wind dips at night, on average, too it doesn't dip nearly as much as demand.

"If you breathed in pure CO2, it would almost instantly kill you", (my quote)

"No, you'd need enough to suffocate you," (Old_C_Code response)

Which part of the word "pure" didn't you understand?If it is PURE CO2, i.e. WITHOUT other gasses mixed in such as oxygen, it WILL be "enough to suffocate you"; and only in a few seconds.

https://toxnet.nl...OCNO+516"Concentrations >10% may cause convulsions, coma and death....ANIMAL STUDIES: Inhalation of air containing 68% carbon dioxide for 5 min caused death from asphyxia in pigs. ..."

-and that 68% carbon dioxide above is WITH O2 mixed in thus PURE CO2 would cause suffocation MUCH faster.

it's not a poison!

I didn't say it was. Obviously, just like with most chemicals, whether its a poison depends on how much is taken in at once. But, regardless, can have too much CO2 in atmosphere than what is good for climate without direct CO2 toxicity to us.

Once you have grown a forest, you aren't capturing (much) more carbon. You are simply replacing the trees that die

This is like saying that a human population will eventually be all adults. Trees are constantly growing, dying, and being replaced.

What I'm trying to express is that using forests to offset continued burning of fossil fuels requires continuous expansion of forests. It takes new forests to sequester additional carbon in tree biomass. Once the trees in a new forest reach maturity, the forest will essentially soak up no additional carbon, the forest reaches a steady state in terms of biomass. Continuously planting new forests to keep up with continued burning of fossil fuels does not scale.

I tried to find out how much carbon does get locked up in the ground (humus and such) during the life cycle of trees, but could not find any sort of figure. Unless the tree captured carbon gets locked up in minerals, the answer seems to be "not much".

Also basing the CCS on trees is asinine there are many plants like hemp that oxygenate at 4 times the rate that trees do. It also lends itself to producing power from the plant you are growing which, yes I know produces more CO2 but at a much lower rate that coal fired. It also produces food and building material at the same time you are sequestering CO2 and it would not have the same drop off as the algorithm used for a forest which stops growing at a certain point.

But if the name of the game is to sequester carbon, where are you going to store all the hemp? At least a forest is a self-sustaining carbon store, as long as it does not experience some catastrophic event such as a fire or having the trees knocked down by a hurricane, etc. Even then, it can regrow. Burning wood or hemp is just biofuel, not carbon storage. Using grown building materials is carbon storage as long as the material stays in solid form. But all things have lifetimes, so how you dispose of the wood in an old house matters. Old barn rotting away? That's the carbon going back to atmosphere. I suspect that most of the carbon in food gets back to the atmosphere pretty quickly, the rest over a longer period of time.

Right, at toxic concentrations. But not at non-toxic concentrations.Same with vitamins. Heard of vitamin poisoning? Would you also say vitamins are poisonous in any amount because they are poisonous in massive amounts? -same logic.CO2 doesn't directly cause us "convulsions, coma and death" at the small concentrations (about 400ppm) in the normal atmosphere.

Coal is essential to the national security of the USA. Can't have national security depending on sun and wind.

Sun & wind enhance security because they cannot be taken away/suffer supply shortages like fossil fuels. Once the generation infrastructure is in place, the supply is unlimited.

Coal is actually a hazard for the country. Fossil fuels are creating conditions what will increasingly directly impact coastal regions and cause damage via shifts suitable agricultural areas. The economic disruptions in poor nations will further fuel unrest and instability, making the world a more dangerous place for us all.

C-code should know that real men program Z80 in hex from memory Not that toy Arduino stuff. Poor old C-code; Wouldn't know C code if it came in a bottle of milk. In a similar fashion, he wouldn't know climate change if his own backyard was on fire after 20 months drought. Similarly, I don't think that C code understands the consequences of global warming on Mankind's ability to prosper in the future. Sad... old rightwing climate deniers losing their marbles slowly on phys.org

other countries with lots more renewable energy in the mix have no issues at all with power stability year round - and none of them have really started in on storage, yet

That's because these "other countries" exist in large interconnected synchronized grids, where the contribution of their renewable energy is still a vanishingly small percentage of the whole. They simply export the variability problem across national borders and deal with it by money.

Or they're one of those countries with a handful of hydroelectric dams handling 80+% of the power demands, so they're technically "renewable". They don't have to invest in storage because they already have huge dispatchable reserves.

The storage problem kicks in at a fairly low levels of renewables integration. That's because the difference between peak and average power (Cp) of wind/solar is very large. With wind power you run into the storage issue when the system penetration is between 20-25%

With solar power the issue is worse. It doesn't benefit from the same sort of random geographical distribution as wind power, because there's only one sun and it's up on the same hour for everyone on the same time zone (~1000 miles)

And with a capacity factor anywhere from 7% to 15% your daily peak output is 6 - 14 times greater than the average output. It works out somewhat if you're near the equator where the peak demand coincides with the sunlight hours, but not at all at northern latitudes where the demand goes up as the sun goes down.

But, individual homeowners can go a long way with hot water storage boilers to shift the energy demand onto the daylight hours. The main issue is that gas is cheaper to heat with. Direct solar heaters would be cheaper for that purpose.

E-mail the story

Coal plant offsets with carbon capture means covering 89 percent of the US in forests

Note

Your email address is used only to let the recipient know who sent the email. Neither your address nor the recipient's address will be used for any other purpose.
The information you enter will appear in your e-mail message and is not retained by Phys.org in any form.

Your message

Newsletter sign up

Get weekly and/or daily updates delivered to your inbox.
You can unsubscribe at any time and we'll never share your details to third parties.

Your Privacy

This site uses cookies to assist with navigation, analyse your use of our services, and provide content from third parties.
By using our site, you acknowledge that you have read and understand our Privacy Policy
and Terms of Use.